/**
 * Objects that can compare pairs of objects (for equality and
 * ordering).  We assume that if something is neither less than
 * or equal to another object, then it is greater than that other
 * object.  Typically used to help with sorting.
 *
 * @author Samuel A. Rebelsky
 * @version 1.1 of October 1999
 */
public interface Comparator {
  /** 
   * Determine if the first element is strictly smaller than the 
   * second.   Throws an exception if the two elements cannot
   * be compared.
   */
  public boolean lessThan(Object first, Object second)
    throws IncomparableException;

  /** 
   * Determine if the first element is equal to the second.   Throws
   * an exception if the two elements cannot be compared.
   */
  public boolean equals(Object first, Object second)
    throws IncomparableException;
  
} // interface Comparator